summaryrefslogtreecommitdiff
path: root/Master/tlpkg/tlperl/lib/Fatal.pm
blob: 09abfb8536d8f80b49b7edfcc8c62afc9d7c6ec4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
package Fatal;

# ABSTRACT: Replace functions with equivalents which succeed or die

use 5.008;  # 5.8.x needed for autodie
use Carp;
use strict;
use warnings;
use Tie::RefHash;   # To cache subroutine refs
use Config;
use Scalar::Util qw(set_prototype looks_like_number);

use autodie::Util qw(
  fill_protos
  install_subs
  make_core_trampoline
  on_end_of_compile_scope
);

use constant PERL510     => ( $] >= 5.010 );

use constant LEXICAL_TAG => q{:lexical};
use constant VOID_TAG    => q{:void};
use constant INSIST_TAG  => q{!};

# Keys for %Cached_fatalised_sub  (used in 3rd level)
use constant CACHE_AUTODIE_LEAK_GUARD    => 0;
use constant CACHE_FATAL_WRAPPER         => 1;
use constant CACHE_FATAL_VOID            => 2;


use constant ERROR_NOARGS    => 'Cannot use lexical %s with no arguments';
use constant ERROR_VOID_LEX  => VOID_TAG.' cannot be used with lexical scope';
use constant ERROR_LEX_FIRST => LEXICAL_TAG.' must be used as first argument';
use constant ERROR_NO_LEX    => "no %s can only start with ".LEXICAL_TAG;
use constant ERROR_BADNAME   => "Bad subroutine name for %s: %s";
use constant ERROR_NOTSUB    => "%s is not a Perl subroutine";
use constant ERROR_NOT_BUILT => "%s is neither a builtin, nor a Perl subroutine";
use constant ERROR_NOHINTS   => "No user hints defined for %s";

use constant ERROR_CANT_OVERRIDE => "Cannot make the non-overridable builtin %s fatal";

use constant ERROR_NO_IPC_SYS_SIMPLE => "IPC::System::Simple required for Fatalised/autodying system()";

use constant ERROR_IPC_SYS_SIMPLE_OLD => "IPC::System::Simple version %f required for Fatalised/autodying system().  We only have version %f";

use constant ERROR_AUTODIE_CONFLICT => q{"no autodie '%s'" is not allowed while "use Fatal '%s'" is in effect};

use constant ERROR_FATAL_CONFLICT => q{"use Fatal '%s'" is not allowed while "no autodie '%s'" is in effect};

use constant ERROR_58_HINTS => q{Non-subroutine %s hints for %s are not supported under Perl 5.8.x};

# Older versions of IPC::System::Simple don't support all the
# features we need.

use constant MIN_IPC_SYS_SIMPLE_VER => 0.12;

our $VERSION = '2.32'; # VERSION: Generated by DZP::OurPkg::Version

our $Debug ||= 0;

# EWOULDBLOCK values for systems that don't supply their own.
# Even though this is defined with our, that's to help our
# test code.  Please don't rely upon this variable existing in
# the future.

our %_EWOULDBLOCK = (
    MSWin32 => 33,
);

$Carp::CarpInternal{'Fatal'} = 1;
$Carp::CarpInternal{'autodie'} = 1;
$Carp::CarpInternal{'autodie::exception'} = 1;

# the linux parisc port has separate EAGAIN and EWOULDBLOCK,
# and the kernel returns EAGAIN
my $try_EAGAIN = ($^O eq 'linux' and $Config{archname} =~ /hppa|parisc/) ? 1 : 0;

# We have some tags that can be passed in for use with import.
# These are all assumed to be CORE::

my %TAGS = (
    ':io'      => [qw(:dbm :file :filesys :ipc :socket
                       read seek sysread syswrite sysseek )],
    ':dbm'     => [qw(dbmopen dbmclose)],
    ':file'    => [qw(open close flock sysopen fcntl binmode
                     ioctl truncate)],
    ':filesys' => [qw(opendir closedir chdir link unlink rename mkdir
                      symlink rmdir readlink chmod chown utime)],
    ':ipc'     => [qw(:msg :semaphore :shm pipe kill)],
    ':msg'     => [qw(msgctl msgget msgrcv msgsnd)],
    ':threads' => [qw(fork)],
    ':semaphore'=>[qw(semctl semget semop)],
    ':shm'     => [qw(shmctl shmget shmread)],
    ':system'  => [qw(system exec)],

    # Can we use qw(getpeername getsockname)? What do they do on failure?
    # TODO - Can socket return false?
    ':socket'  => [qw(accept bind connect getsockopt listen recv send
                   setsockopt shutdown socketpair)],

    # Our defaults don't include system(), because it depends upon
    # an optional module, and it breaks the exotic form.
    #
    # This *may* change in the future.  I'd love IPC::System::Simple
    # to be a dependency rather than a recommendation, and hence for
    # system() to be autodying by default.

    ':default' => [qw(:io :threads)],

    # Everything in v2.07 and before. This was :default less chmod and chown
    ':v207'    => [qw(:threads :dbm :socket read seek sysread
                   syswrite sysseek open close flock sysopen fcntl fileno
                   binmode ioctl truncate opendir closedir chdir link unlink
                   rename mkdir symlink rmdir readlink umask
                   :msg :semaphore :shm pipe)],

    # Chmod was added in 2.13
    ':v213'    => [qw(:v207 chmod)],

    # chown, utime, kill were added in 2.14
    ':v214'    => [qw(:v213 chown utime kill)],

    # umask was removed in 2.26
    ':v225' => [qw(:io :threads umask fileno)],

    # Version specific tags.  These allow someone to specify
    # use autodie qw(:1.994) and know exactly what they'll get.

    ':1.994' => [qw(:v207)],
    ':1.995' => [qw(:v207)],
    ':1.996' => [qw(:v207)],
    ':1.997' => [qw(:v207)],
    ':1.998' => [qw(:v207)],
    ':1.999' => [qw(:v207)],
    ':1.999_01' => [qw(:v207)],
    ':2.00'  => [qw(:v207)],
    ':2.01'  => [qw(:v207)],
    ':2.02'  => [qw(:v207)],
    ':2.03'  => [qw(:v207)],
    ':2.04'  => [qw(:v207)],
    ':2.05'  => [qw(:v207)],
    ':2.06'  => [qw(:v207)],
    ':2.06_01' => [qw(:v207)],
    ':2.07'  => [qw(:v207)],     # Last release without chmod
    ':2.08'  => [qw(:v213)],
    ':2.09'  => [qw(:v213)],
    ':2.10'  => [qw(:v213)],
    ':2.11'  => [qw(:v213)],
    ':2.12'  => [qw(:v213)],
    ':2.13'  => [qw(:v213)],     # Last release without chown
    ':2.14'  => [qw(:v225)],
    ':2.15'  => [qw(:v225)],
    ':2.16'  => [qw(:v225)],
    ':2.17'  => [qw(:v225)],
    ':2.18'  => [qw(:v225)],
    ':2.19'  => [qw(:v225)],
    ':2.20'  => [qw(:v225)],
    ':2.21'  => [qw(:v225)],
    ':2.22'  => [qw(:v225)],
    ':2.23'  => [qw(:v225)],
    ':2.24'  => [qw(:v225)],
    ':2.25'  => [qw(:v225)],
    ':2.26'  => [qw(:default)],
    ':2.27'  => [qw(:default)],
    ':2.28'  => [qw(:default)],
    ':2.29'  => [qw(:default)],
    ':2.30'  => [qw(:default)],
    ':2.31'  => [qw(:default)],
    ':2.32'  => [qw(:default)],
);


{
    # Expand :all immediately by expanding and flattening all tags.
    # _expand_tag is not really optimised for expanding the ":all"
    # case (i.e. keys %TAGS, or values %TAGS for that matter), so we
    # just do it here.
    #
    # NB: The %tag_cache/_expand_tag relies on $TAGS{':all'} being
    # pre-expanded.
    my %seen;
    my @all = grep {
        !/^:/ && !$seen{$_}++
    } map { @{$_} } values %TAGS;
    $TAGS{':all'} = \@all;
}

# This hash contains subroutines for which we should
# subroutine() // die() rather than subroutine() || die()

my %Use_defined_or;

# CORE::open returns undef on failure.  It can legitimately return
# 0 on success, eg: open(my $fh, '-|') || exec(...);

@Use_defined_or{qw(
    CORE::fork
    CORE::recv
    CORE::send
    CORE::open
    CORE::fileno
    CORE::read
    CORE::readlink
    CORE::sysread
    CORE::syswrite
    CORE::sysseek
    CORE::umask
)} = ();

# Some functions can return true because they changed *some* things, but
# not all of them.  This is a list of offending functions, and how many
# items to subtract from @_ to determine the "success" value they return.

my %Returns_num_things_changed = (
    'CORE::chmod'  => 1,
    'CORE::chown'  => 2,
    'CORE::kill'   => 1,  # TODO: Could this return anything on negative args?
    'CORE::unlink' => 0,
    'CORE::utime'  => 2,
);

# Optional actions to take on the return value before returning it.

my %Retval_action = (
    "CORE::open"        => q{

    # apply the open pragma from our caller
    if( defined $retval && !( @_ >= 3 && $_[1] =~ /:/ )) {
        # Get the caller's hint hash
        my $hints = (caller 0)[10];

        # Decide if we're reading or writing and apply the appropriate encoding
        # These keys are undocumented.
        # Match what PerlIO_context_layers() does.  Read gets the read layer,
        # everything else gets the write layer.
        my $encoding = $_[1] =~ /^\+?>/ ? $hints->{"open>"} : $hints->{"open<"};

        # Apply the encoding, if any.
        if( $encoding ) {
            binmode $_[0], $encoding;
        }
    }

},
    "CORE::sysopen"     => q{

    # apply the open pragma from our caller
    if( defined $retval ) {
        # Get the caller's hint hash
        my $hints = (caller 0)[10];

        require Fcntl;

        # Decide if we're reading or writing and apply the appropriate encoding.
        # Match what PerlIO_context_layers() does.  Read gets the read layer,
        # everything else gets the write layer.
        my $open_read_only = !($_[2] ^ Fcntl::O_RDONLY());
        my $encoding = $open_read_only ? $hints->{"open<"} : $hints->{"open>"};

        # Apply the encoding, if any.
        if( $encoding ) {
            binmode $_[0], $encoding;
        }
    }

},
);

my %reusable_builtins;

# "Wait!" I hear you cry, "truncate() and chdir() are not reuseable! They can
# take file and directory handles, which are package depedent."
#
# You would be correct, except that prototype() returns signatures which don't
# allow for passing of globs, and nobody's complained about that. You can
# still use \*FILEHANDLE, but that results in a reference coming through,
# and it's already pointing to the filehandle in the caller's packge, so
# it's all okay.

@reusable_builtins{qw(
    CORE::fork
    CORE::kill
    CORE::truncate
    CORE::chdir
    CORE::link
    CORE::unlink
    CORE::rename
    CORE::mkdir
    CORE::symlink
    CORE::rmdir
    CORE::readlink
    CORE::umask
    CORE::chmod
    CORE::chown
    CORE::utime
    CORE::msgctl
    CORE::msgget
    CORE::msgrcv
    CORE::msgsnd
    CORE::semctl
    CORE::semget
    CORE::semop
    CORE::shmctl
    CORE::shmget
    CORE::shmread
    CORE::exec
    CORE::system
)} = ();

# Cached_fatalised_sub caches the various versions of our
# fatalised subs as they're produced.  This means we don't
# have to build our own replacement of CORE::open and friends
# for every single package that wants to use them.

my %Cached_fatalised_sub = ();

# Every time we're called with package scope, we record the subroutine
# (including package or CORE::) in %Package_Fatal.  This allows us
# to detect illegal combinations of autodie and Fatal, and makes sure
# we don't accidently make a Fatal function autodying (which isn't
# very useful).

my %Package_Fatal = ();

# The first time we're called with a user-sub, we cache it here.
# In the case of a "no autodie ..." we put back the cached copy.

my %Original_user_sub = ();

# Is_fatalised_sub simply records a big map of fatalised subroutine
# refs.  It means we can avoid repeating work, or fatalising something
# we've already processed.

my  %Is_fatalised_sub = ();
tie %Is_fatalised_sub, 'Tie::RefHash';

# Our trampoline cache allows us to cache trampolines which are used to
# bounce leaked wrapped core subroutines to their actual core counterparts.

my %Trampoline_cache;

# A cache mapping "CORE::<name>" to their prototype.  Turns out that if
# you "use autodie;" enough times, this pays off.
my %CORE_prototype_cache;

# We use our package in a few hash-keys.  Having it in a scalar is
# convenient.  The "guard $PACKAGE" string is used as a key when
# setting up lexical guards.

my $PACKAGE       = __PACKAGE__;
my $NO_PACKAGE    = "no $PACKAGE";      # Used to detect 'no autodie'

# Here's where all the magic happens when someone write 'use Fatal'
# or 'use autodie'.

sub import {
    my $class        = shift(@_);
    my @original_args = @_;
    my $void         = 0;
    my $lexical      = 0;
    my $insist_hints = 0;

    my ($pkg, $filename) = caller();

    @_ or return;   # 'use Fatal' is a no-op.

    # If we see the :lexical flag, then _all_ arguments are
    # changed lexically

    if ($_[0] eq LEXICAL_TAG) {
        $lexical = 1;
        shift @_;

        # It is currently an implementation detail that autodie is
        # implemented as "use Fatal qw(:lexical ...)".  For backwards
        # compatibility, we allow it - but not without a warning.
        # NB: Optimise for autodie as it is quite possibly the most
        # freq. consumer of this case.
        if ($class ne 'autodie' and not $class->isa('autodie')) {
            if ($class eq 'Fatal') {
                warnings::warnif(
                    'deprecated',
                    '[deprecated] The "use Fatal qw(:lexical ...)" '
                    . 'should be replaced by "use autodie qw(...)". '
                    . 'Seen' # warnif appends " at <...>"
                    );
            } else {
                warnings::warnif(
                    'deprecated',
                    "[deprecated] The class/Package $class is a "
                    . 'subclass of Fatal and used the :lexical. '
                    . 'If $class provides lexical error checking '
                    . 'it should extend autodie instead of using :lexical. '
                    . 'Seen' # warnif appends " at <...>"
                    );
            }
            # "Promote" the call to autodie from here on.  This is
            # already mostly the case (e.g. use Fatal qw(:lexical ...)
            # would throw autodie::exceptions on error rather than the
            # Fatal errors.
            $class = 'autodie';
            # This requires that autodie is in fact loaded; otherwise
            # the "$class->X()" method calls below will explode.
            require autodie;
            # TODO, when autodie and Fatal are cleanly separated, we
            # should go a "goto &autodie::import" here instead.
        }

        # If we see no arguments and :lexical, we assume they
        # wanted ':default'.

        if (@_ == 0) {
            push(@_, ':default');
        }

        # Don't allow :lexical with :void, it's needlessly confusing.
        if ( grep { $_ eq VOID_TAG } @_ ) {
            croak(ERROR_VOID_LEX);
        }
    }

    if ( grep { $_ eq LEXICAL_TAG } @_ ) {
        # If we see the lexical tag as the non-first argument, complain.
        croak(ERROR_LEX_FIRST);
    }

    my @fatalise_these =  @_;

    # These subs will get unloaded at the end of lexical scope.
    my %unload_later;
    # These subs are to be installed into callers namespace.
    my %install_subs;

    # Use _translate_import_args to expand tags for us.  It will
    # pass-through unknown tags (i.e. we have to manually handle
    # VOID_TAG).
    #
    # NB: _translate_import_args re-orders everything for us, so
    # we don't have to worry about stuff like:
    #
    #     :default :void :io
    #
    # That will (correctly) translated into
    #
    #     expand(:defaults-without-io) :void :io
    #
    # by _translate_import_args.
    for my $func ($class->_translate_import_args(@fatalise_these)) {

        if ($func eq VOID_TAG) {

            # When we see :void, set the void flag.
            $void = 1;

        } elsif ($func eq INSIST_TAG) {

            $insist_hints = 1;

        } else {

            # Otherwise, fatalise it.

            # Check to see if there's an insist flag at the front.
            # If so, remove it, and insist we have hints for this sub.
            my $insist_this = $insist_hints;

            if (substr($func, 0, 1) eq '!') {
                $func = substr($func, 1);
                $insist_this = 1;
            }

            # We're going to make a subroutine fatalistic.
            # However if we're being invoked with 'use Fatal qw(x)'
            # and we've already been called with 'no autodie qw(x)'
            # in the same scope, we consider this to be an error.
            # Mixing Fatal and autodie effects was considered to be
            # needlessly confusing on p5p.

            my $sub = $func;
            $sub = "${pkg}::$sub" unless $sub =~ /::/;

            # If we're being called as Fatal, and we've previously
            # had a 'no X' in scope for the subroutine, then complain
            # bitterly.

            if (! $lexical and $^H{$NO_PACKAGE}{$sub}) {
                 croak(sprintf(ERROR_FATAL_CONFLICT, $func, $func));
            }

            # We're not being used in a confusing way, so make
            # the sub fatal.  Note that _make_fatal returns the
            # old (original) version of the sub, or undef for
            # built-ins.

            my $sub_ref = $class->_make_fatal(
                $func, $pkg, $void, $lexical, $filename,
                $insist_this, \%install_subs,
            );

            $Original_user_sub{$sub} ||= $sub_ref;

            # If we're making lexical changes, we need to arrange
            # for them to be cleaned at the end of our scope, so
            # record them here.

            $unload_later{$func} = $sub_ref if $lexical;
        }
    }

    install_subs($pkg, \%install_subs);

    if ($lexical) {

        # Dark magic to have autodie work under 5.8
        # Copied from namespace::clean, that copied it from
        # autobox, that found it on an ancient scroll written
        # in blood.

        # This magic bit causes %^H to be lexically scoped.

        $^H |= 0x020000;

        # Our package guard gets invoked when we leave our lexical
        # scope.

        on_end_of_compile_scope(sub {
            install_subs($pkg, \%unload_later);
        });

        # To allow others to determine when autodie was in scope,
        # and with what arguments, we also set a %^H hint which
        # is how we were called.

        # This feature should be considered EXPERIMENTAL, and
        # may change without notice.  Please e-mail pjf@cpan.org
        # if you're actually using it.

        $^H{autodie} = "$PACKAGE @original_args";

    }

    return;

}

sub unimport {
    my $class = shift;

    # Calling "no Fatal" must start with ":lexical"
    if ($_[0] ne LEXICAL_TAG) {
        croak(sprintf(ERROR_NO_LEX,$class));
    }

    shift @_;   # Remove :lexical

    my $pkg = (caller)[0];

    # If we've been called with arguments, then the developer
    # has explicitly stated 'no autodie qw(blah)',
    # in which case, we disable Fatalistic behaviour for 'blah'.

    my @unimport_these = @_ ? @_ : ':all';
    my (%uninstall_subs, %reinstall_subs);

    for my $symbol ($class->_translate_import_args(@unimport_these)) {

        my $sub = $symbol;
        $sub = "${pkg}::$sub" unless $sub =~ /::/;

        # If 'blah' was already enabled with Fatal (which has package
        # scope) then, this is considered an error.

        if (exists $Package_Fatal{$sub}) {
            croak(sprintf(ERROR_AUTODIE_CONFLICT,$symbol,$symbol));
        }

        # Record 'no autodie qw($sub)' as being in effect.
        # This is to catch conflicting semantics elsewhere
        # (eg, mixing Fatal with no autodie)

        $^H{$NO_PACKAGE}{$sub} = 1;
        # Record the current sub to be reinstalled at end of scope
        # and then restore the original (can be undef for "CORE::"
        # subs)

        {
            no strict 'refs';  ## no critic # to avoid: Can't use string (...) as a symbol ref ...
            $reinstall_subs{$symbol} = \&$sub
                if exists ${"${pkg}::"}{$symbol};
        }
        $uninstall_subs{$symbol} = $Original_user_sub{$sub};

    }

    install_subs($pkg, \%uninstall_subs);
    on_end_of_compile_scope(sub {
        install_subs($pkg, \%reinstall_subs);
    });

    return;

}

sub _translate_import_args {
    my ($class, @args) = @_;
    my @result;
    my %seen;

    if (@args < 2) {
        # Optimize for this case, as it is fairly common.  (e.g. use
        # autodie; or use autodie qw(:all); both trigger this).
        return unless @args;

        # Not a (known) tag, pass through.
        return @args unless exists($TAGS{$args[0]});

        # Strip "CORE::" from all elements in the list as import and
        # unimport does not handle the "CORE::" prefix too well.
        #
        # NB: we use substr as it is faster than s/^CORE::// and
        # it does not change the elements.
        return map { substr($_, 6) } @{ $class->_expand_tag($args[0]) };
    }

    # We want to translate
    #
    #     :default :void :io
    #
    # into (pseudo-ish):
    #
    #     expanded(:threads) :void expanded(:io)
    #
    # We accomplish this by "reverse, expand + filter, reverse".
    for my $a (reverse(@args)) {
        if (exists $TAGS{$a}) {
            my $expanded = $class->_expand_tag($a);
            push(@result,
                 # Remove duplicates after ...
                 grep { !$seen{$_}++ }
                 # we have stripped CORE:: (see above)
                 map { substr($_, 6) }
                 # We take the elements in reverse order
                 # (as @result be reversed later).
                 reverse(@{$expanded}));
        } else {
            # pass through - no filtering here for tags.
            #
            # The reason for not filtering tags cases like:
            #
            #    ":default :void :io :void :threads"
            #
            # As we have reversed args, we see this as:
            #
            #    ":threads :void :io :void* :default*"
            #
            # (Entries marked with "*" will be filtered out completely).  When
            # reversed again, this will be:
            #
            #    ":io :void :threads"
            #
            # But we would rather want it to be:
            #
            #    ":void :io :threads" or ":void :io :void :threads"
            #

            my $letter = substr($a, 0, 1);
            if ($letter ne ':' && $a ne INSIST_TAG) {
                next if $seen{$a}++;
                if ($letter eq '!' and $seen{substr($a, 1)}++) {
                    my $name = substr($a, 1);
                    # People are being silly and doing:
                    #
                    #    use autodie qw(!a a);
                    #
                    # Enjoy this little O(n) clean up...
                    @result = grep { $_ ne $name } @result;
                }
            }
            push @result, $a;
        }
    }
    # Reverse the result to restore the input order
    return reverse(@result);
}


# NB: Perl::Critic's dump-autodie-tag-contents depends upon this
# continuing to work.

{
    # We assume that $TAGS{':all'} is pre-expanded and just fill it in
    # from the beginning.
    my %tag_cache = (
        'all' => [map { "CORE::$_" } @{$TAGS{':all'}}],
    );

    # Expand a given tag (e.g. ":default") into a listref containing
    # all sub names covered by that tag.  Each sub is returned as
    # "CORE::<name>" (i.e. "CORE::open" rather than "open").
    #
    # NB: the listref must not be modified.
    sub _expand_tag {
        my ($class, $tag) = @_;

        if (my $cached = $tag_cache{$tag}) {
            return $cached;
        }

        if (not exists $TAGS{$tag}) {
            croak "Invalid exception class $tag";
        }

        my @to_process = @{$TAGS{$tag}};

        # If the tag is basically an alias of another tag (like e.g. ":2.11"),
        # then just share the resulting reference with the original content (so
        # we only pay for an extra reference for the alias memory-wise).
        if (@to_process == 1 && substr($to_process[0], 0, 1) eq ':') {
            # We could do this for "non-tags" as well, but that only occurs
            # once at the time of writing (":threads" => ["fork"]), so
            # probably not worth it.
            my $expanded = $class->_expand_tag($to_process[0]);
            $tag_cache{$tag} = $expanded;
            return $expanded;
        }

        my %seen = ();
        my @taglist = ();

        for my $item (@to_process) {
            # substr is more efficient than m/^:/ for stuff like this,
            # at the price of being a bit more verbose/low-level.
            if (substr($item, 0, 1) eq ':') {
                # Use recursion here to ensure we expand a tag at most once.

                my $expanded = $class->_expand_tag($item);
                push @taglist, grep { !$seen{$_}++ } @{$expanded};
            } else {
                my $subname = "CORE::$item";
                push @taglist, $subname
                    unless $seen{$subname}++;
            }
        }

        $tag_cache{$tag} = \@taglist;

        return \@taglist;

    }

}

# This is a backwards compatible version of _write_invocation.  It's
# recommended you don't use it.

sub write_invocation {
    my ($core, $call, $name, $void, @args) = @_;

    return Fatal->_write_invocation(
        $core, $call, $name, $void,
        0,      # Lexical flag
        undef,  # Sub, unused in legacy mode
        undef,  # Subref, unused in legacy mode.
        @args
    );
}

# This version of _write_invocation is used internally.  It's not
# recommended you call it from external code, as the interface WILL
# change in the future.

sub _write_invocation {

    my ($class, $core, $call, $name, $void, $lexical, $sub, $sref, @argvs) = @_;

    if (@argvs == 1) {        # No optional arguments

        my @argv = @{$argvs[0]};
        shift @argv;

        return $class->_one_invocation($core,$call,$name,$void,$sub,! $lexical, $sref, @argv);

    } else {
        my $else = "\t";
        my (@out, @argv, $n);
        while (@argvs) {
            @argv = @{shift @argvs};
            $n = shift @argv;

            my $condition = "\@_ == $n";

            if (@argv and $argv[-1] =~ /[#@]_/) {
                # This argv ends with '@' in the prototype, so it matches
                # any number of args >= the number of expressions in the
                # argv.
                $condition = "\@_ >= $n";
            }

            push @out, "${else}if ($condition) {\n";

            $else = "\t} els";

        push @out, $class->_one_invocation($core,$call,$name,$void,$sub,! $lexical, $sref, @argv);
        }
        push @out, qq[
            }
            die "Internal error: $name(\@_): Do not expect to get ", scalar(\@_), " arguments";
    ];

        return join '', @out;
    }
}


# This is a slim interface to ensure backward compatibility with
# anyone doing very foolish things with old versions of Fatal.

sub one_invocation {
    my ($core, $call, $name, $void, @argv) = @_;

    return Fatal->_one_invocation(
        $core, $call, $name, $void,
        undef,   # Sub.  Unused in back-compat mode.
        1,       # Back-compat flag
        undef,   # Subref, unused in back-compat mode.
        @argv
    );

}

# This is the internal interface that generates code.
# NOTE: This interface WILL change in the future.  Please do not
# call this subroutine directly.

# TODO: Whatever's calling this code has already looked up hints.  Pass
# them in, rather than look them up a second time.

sub _one_invocation {
    my ($class, $core, $call, $name, $void, $sub, $back_compat, $sref, @argv) = @_;


    # If someone is calling us directly (a child class perhaps?) then
    # they could try to mix void without enabling backwards
    # compatibility.  We just don't support this at all, so we gripe
    # about it rather than doing something unwise.

    if ($void and not $back_compat) {
        Carp::confess("Internal error: :void mode not supported with $class");
    }

    # @argv only contains the results of the in-built prototype
    # function, and is therefore safe to interpolate in the
    # code generators below.

    # TODO - The following clobbers context, but that's what the
    #        old Fatal did.  Do we care?

    if ($back_compat) {

        # Use Fatal qw(system) will never be supported.  It generated
        # a compile-time error with legacy Fatal, and there's no reason
        # to support it when autodie does a better job.

        if ($call eq 'CORE::system') {
            return q{
                croak("UNIMPLEMENTED: use Fatal qw(system) not supported.");
            };
        }

        local $" = ', ';

        if ($void) {
            return qq/return (defined wantarray)?$call(@argv):
                   $call(@argv) || Carp::croak("Can't $name(\@_)/ .
                   ($core ? ': $!' : ', \$! is \"$!\"') . '")'
        } else {
            return qq{return $call(@argv) || Carp::croak("Can't $name(\@_)} .
                   ($core ? ': $!' : ', \$! is \"$!\"') . '")';
        }
    }

    # The name of our original function is:
    #   $call if the function is CORE
    #   $sub if our function is non-CORE

    # The reason for this is that $call is what we're actually
    # calling.  For our core functions, this is always
    # CORE::something.  However for user-defined subs, we're about to
    # replace whatever it is that we're calling; as such, we actually
    # calling a subroutine ref.

    my $human_sub_name = $core ? $call : $sub;

    # Should we be testing to see if our result is defined, or
    # just true?

    my $use_defined_or;

    my $hints;      # All user-sub hints, including list hints.

    if ( $core ) {

        # Core hints are built into autodie.

        $use_defined_or = exists ( $Use_defined_or{$call} );

    }
    else {

        # User sub hints are looked up using autodie::hints,
        # since users may wish to add their own hints.

        require autodie::hints;

        $hints = autodie::hints->get_hints_for( $sref );

        # We'll look up the sub's fullname.  This means we
        # get better reports of where it came from in our
        # error messages, rather than what imported it.

        $human_sub_name = autodie::hints->sub_fullname( $sref );

    }

    # Checks for special core subs.

    if ($call eq 'CORE::system') {

        # Leverage IPC::System::Simple if we're making an autodying
        # system.

        local $" = ", ";

        # We need to stash $@ into $E, rather than using
        # local $@ for the whole sub.  If we don't then
        # any exceptions from internal errors in autodie/Fatal
        # will mysteriously disappear before propagating
        # upwards.

        return qq{
            my \$retval;
            my \$E;


            {
                local \$@;

                eval {
                    \$retval = IPC::System::Simple::system(@argv);
                };

                \$E = \$@;
            }

            if (\$E) {

                # TODO - This can't be overridden in child
                # classes!

                die autodie::exception::system->new(
                    function => q{CORE::system}, args => [ @argv ],
                    message => "\$E", errno => \$!,
                );
            }

            return \$retval;
        };

    }

    local $" = ', ';

    # If we're going to throw an exception, here's the code to use.
    my $die = qq{
        die $class->throw(
            function => q{$human_sub_name}, args => [ @argv ],
            pragma => q{$class}, errno => \$!,
            context => \$context, return => \$retval,
            eval_error => \$@
        )
    };

    if ($call eq 'CORE::flock') {

        # flock needs special treatment.  When it fails with
        # LOCK_UN and EWOULDBLOCK, then it's not really fatal, it just
        # means we couldn't get the lock right now.

        require POSIX;      # For POSIX::EWOULDBLOCK

        local $@;   # Don't blat anyone else's $@.

        # Ensure that our vendor supports EWOULDBLOCK.  If they
        # don't (eg, Windows), then we use known values for its
        # equivalent on other systems.

        my $EWOULDBLOCK = eval { POSIX::EWOULDBLOCK(); }
                          || $_EWOULDBLOCK{$^O}
                          || _autocroak("Internal error - can't overload flock - EWOULDBLOCK not defined on this system.");
        my $EAGAIN = $EWOULDBLOCK;
        if ($try_EAGAIN) {
            $EAGAIN = eval { POSIX::EAGAIN(); }
                          || _autocroak("Internal error - can't overload flock - EAGAIN not defined on this system.");
        }

        require Fcntl;      # For Fcntl::LOCK_NB

        return qq{

            my \$context = wantarray() ? "list" : "scalar";

            # Try to flock.  If successful, return it immediately.

            my \$retval = $call(@argv);
            return \$retval if \$retval;

            # If we failed, but we're using LOCK_NB and
            # returned EWOULDBLOCK, it's not a real error.

            if (\$_[1] & Fcntl::LOCK_NB() and
                (\$! == $EWOULDBLOCK or
                ($try_EAGAIN and \$! == $EAGAIN ))) {
                return \$retval;
            }

            # Otherwise, we failed.  Die noisily.

            $die;

        };
    }

    if ($call eq 'CORE::kill') {

        return qq[

            my \$num_things = \@_ - $Returns_num_things_changed{$call};
            my \$context = ! defined wantarray() ? 'void' : 'scalar';
            my \$signal = \$_[0];
            my \$retval = $call(@argv);
            my \$sigzero = looks_like_number( \$signal ) && \$signal == 0;

            if (    (   \$sigzero && \$context eq 'void' )
                 or ( ! \$sigzero && \$retval != \$num_things ) ) {

                $die;
            }

            return \$retval;
        ];
    }

    if (exists $Returns_num_things_changed{$call}) {

        # Some things return the number of things changed (like
        # chown, kill, chmod, etc). We only consider these successful
        # if *all* the things are changed.

        return qq[
            my \$num_things = \@_ - $Returns_num_things_changed{$call};
            my \$retval = $call(@argv);

            if (\$retval != \$num_things) {

                # We need \$context to throw an exception.
                # It's *always* set to scalar, because that's how
                # autodie calls chown() above.

                my \$context = "scalar";
                $die;
            }

            return \$retval;
        ];
    }

    # AFAIK everything that can be given an unopned filehandle
    # will fail if it tries to use it, so we don't really need
    # the 'unopened' warning class here.  Especially since they
    # then report the wrong line number.

    # Other warnings are disabled because they produce excessive
    # complaints from smart-match hints under 5.10.1.

    my $code = qq[
        no warnings qw(unopened uninitialized numeric);
        no if \$\] >= 5.017011, warnings => "experimental::smartmatch";

        if (wantarray) {
            my \@results = $call(@argv);
            my \$retval  = \\\@results;
            my \$context = "list";

    ];

    my $retval_action = $Retval_action{$call} || '';

    if ( $hints and ( ref($hints->{list} ) || "" ) eq 'CODE' ) {

        # NB: Subroutine hints are passed as a full list.
        # This differs from the 5.10.0 smart-match behaviour,
        # but means that context unaware subroutines can use
        # the same hints in both list and scalar context.

        $code .= qq{
            if ( \$hints->{list}->(\@results) ) { $die };
        };
    }
    elsif ( PERL510 and $hints ) {
        $code .= qq{
            if ( \@results ~~ \$hints->{list} ) { $die };
        };
    }
    elsif ( $hints ) {
        croak sprintf(ERROR_58_HINTS, 'list', $sub);
    }
    else {
        $code .= qq{
            # An empty list, or a single undef is failure
            if (! \@results or (\@results == 1 and ! defined \$results[0])) {
                $die;
            }
        }
    }

    # Tidy up the end of our wantarray call.

    $code .= qq[
            return \@results;
        }
    ];


    # Otherwise, we're in scalar context.
    # We're never in a void context, since we have to look
    # at the result.

    $code .= qq{
        my \$retval  = $call(@argv);
        my \$context = "scalar";
    };

    if ( $hints and ( ref($hints->{scalar} ) || "" ) eq 'CODE' ) {

        # We always call code refs directly, since that always
        # works in 5.8.x, and always works in 5.10.1

        return $code .= qq{
            if ( \$hints->{scalar}->(\$retval) ) { $die };
            $retval_action
            return \$retval;
        };

    }
    elsif (PERL510 and $hints) {
        return $code . qq{

            if ( \$retval ~~ \$hints->{scalar} ) { $die };
            $retval_action
            return \$retval;
        };
    }
    elsif ( $hints ) {
        croak sprintf(ERROR_58_HINTS, 'scalar', $sub);
    }

    return $code .
    ( $use_defined_or ? qq{

        $die if not defined \$retval;
        $retval_action
        return \$retval;

    } : qq{

        $retval_action
        return \$retval || $die;

    } ) ;

}

# This returns the old copy of the sub, so we can
# put it back at end of scope.

# TODO : Check to make sure prototypes are restored correctly.

# TODO: Taking a huge list of arguments is awful.  Rewriting to
#       take a hash would be lovely.

# TODO - BACKCOMPAT - This is not yet compatible with 5.10.0

sub _make_fatal {
    my($class, $sub, $pkg, $void, $lexical, $filename, $insist, $install_subs) = @_;
    my($code, $sref, $proto, $core, $call, $hints, $cache, $cache_type);
    my $ini = $sub;
    my $name = $sub;


    if (index($sub, '::') == -1) {
        $sub = "${pkg}::$sub";
        if (substr($name, 0, 1) eq '&') {
            $name = substr($name, 1);
        }
    } else {
        $name =~ s/.*:://;
    }


    # Figure if we're using lexical or package semantics and
    # twiddle the appropriate bits.

    if (not $lexical) {
        $Package_Fatal{$sub} = 1;
    }

    # TODO - We *should* be able to do skipping, since we know when
    # we've lexicalised / unlexicalised a subroutine.


    warn  "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug;
    croak(sprintf(ERROR_BADNAME, $class, $name)) unless $name =~ /^\w+$/;

    if (defined(&$sub)) {   # user subroutine

        # NOTE: Previously we would localise $@ at this point, so
        # the following calls to eval {} wouldn't interfere with anything
        # that's already in $@.  Unfortunately, it would also stop
        # any of our croaks from triggering(!), which is even worse.

        # This could be something that we've fatalised that
        # was in core.

	# Store the current sub in case we need to restore it.
	$sref = \&$sub;

        if ( $Package_Fatal{$sub} and exists($CORE_prototype_cache{"CORE::$name"})) {

            # Something we previously made Fatal that was core.
            # This is safe to replace with an autodying to core
            # version.

            $core  = 1;
            $call  = "CORE::$name";
            $proto = $CORE_prototype_cache{$call};

            # We return our $sref from this subroutine later
            # on, indicating this subroutine should be placed
            # back when we're finished.



        } else {

            # If this is something we've already fatalised or played with,
            # then look-up the name of the original sub for the rest of
            # our processing.

            if (exists($Is_fatalised_sub{$sref})) {
                # $sub is one of our wrappers around a CORE sub or a
                # user sub.  Instead of wrapping our wrapper, lets just
                # generate a new wrapper for the original sub.
                # - NB: the current wrapper might be for a different class
                #   than the one we are generating now (e.g. some limited
                #   mixing between use Fatal + use autodie can occur).
                # - Even for nested autodie, we need this as the leak guards
                #   differ.
                my $s = $Is_fatalised_sub{$sref};
                if (defined($s)) {
                    # It is a wrapper for a user sub
                    $sub = $s;
                } else {
                    # It is a wrapper for a CORE:: sub
                    $core = 1;
                    $call = "CORE::$name";
                    $proto = $CORE_prototype_cache{$call};
                }
            }

            # A regular user sub, or a user sub wrapping a
            # core sub.

            if (!$core) {
                # A non-CORE sub might have hints and such...
                $proto = prototype($sref);
                $call = '&$sref';
                require autodie::hints;

                $hints = autodie::hints->get_hints_for( $sref );

                # If we've insisted on hints, but don't have them, then
                # bail out!

                if ($insist and not $hints) {
                    croak(sprintf(ERROR_NOHINTS, $name));
                }

                # Otherwise, use the default hints if we don't have
                # any.

                $hints ||= autodie::hints::DEFAULT_HINTS();
            }

        }

    } elsif ($sub eq $ini && $sub !~ /^CORE::GLOBAL::/) {
        # Stray user subroutine
        croak(sprintf(ERROR_NOTSUB,$sub));

    } elsif ($name eq 'system') {

        # If we're fatalising system, then we need to load
        # helper code.

        # The business with $E is to avoid clobbering our caller's
        # $@, and to avoid $@ being localised when we croak.

        my $E;

        {
            local $@;

            eval {
                require IPC::System::Simple; # Only load it if we need it.
                require autodie::exception::system;
            };
            $E = $@;
        }

        if ($E) { croak ERROR_NO_IPC_SYS_SIMPLE; }

        # Make sure we're using a recent version of ISS that actually
        # support fatalised system.
        if ($IPC::System::Simple::VERSION < MIN_IPC_SYS_SIMPLE_VER) {
            croak sprintf(
            ERROR_IPC_SYS_SIMPLE_OLD, MIN_IPC_SYS_SIMPLE_VER,
            $IPC::System::Simple::VERSION
            );
        }

        $call = 'CORE::system';
        $core = 1;

    } elsif ($name eq 'exec') {
        # Exec doesn't have a prototype.  We don't care.  This
        # breaks the exotic form with lexical scope, and gives
        # the regular form a "do or die" behavior as expected.

        $call = 'CORE::exec';
        $core = 1;

    } else {            # CORE subroutine
        $call = "CORE::$name";
        if (exists($CORE_prototype_cache{$call})) {
            $proto = $CORE_prototype_cache{$call};
        } else {
            my $E;
            {
                local $@;
                $proto = eval { prototype $call };
                $E = $@;
            }
            croak(sprintf(ERROR_NOT_BUILT,$name)) if $E;
            croak(sprintf(ERROR_CANT_OVERRIDE,$name)) if not defined $proto;
            $CORE_prototype_cache{$call} = $proto;
        }
        $core = 1;
    }

    # TODO: This caching works, but I don't like using $void and
    # $lexical as keys.  In particular, I suspect our code may end up
    # wrapping already wrapped code when autodie and Fatal are used
    # together.

    # NB: We must use '$sub' (the name plus package) and not
    # just '$name' (the short name) here.  Failing to do so
    # results code that's in the wrong package, and hence has
    # access to the wrong package filehandles.

    $cache = $Cached_fatalised_sub{$class}{$sub};
    if ($lexical) {
        $cache_type = CACHE_AUTODIE_LEAK_GUARD;
    } else {
        $cache_type = CACHE_FATAL_WRAPPER;
        $cache_type = CACHE_FATAL_VOID if $void;
    }

    if (my $subref = $cache->{$cache_type}) {
        $install_subs->{$name} = $subref;
        return $sref;
    }

    # If our subroutine is reusable (ie, not package depdendent),
    # then check to see if we've got a cached copy, and use that.
    # See RT #46984. (Thanks to Niels Thykier for being awesome!)

    if ($core && exists $reusable_builtins{$call}) {
        # For non-lexical subs, we can just use this cache directly
        # - for lexical variants, we need a leak guard as well.
        $code = $reusable_builtins{$call}{$lexical};
        if (!$lexical && defined($code)) {
            $install_subs->{$name} = $code;
            return $sref;
        }
    }

    if (!($lexical && $core) && !defined($code)) {
        # No code available, generate it now.
        my $wrapper_pkg = $pkg;
        $wrapper_pkg = undef if (exists($reusable_builtins{$call}));
        $code = $class->_compile_wrapper($wrapper_pkg, $core, $call, $name,
                                         $void, $lexical, $sub, $sref,
                                         $hints, $proto);
        if (!defined($wrapper_pkg)) {
            # cache it so we don't recompile this part again
            $reusable_builtins{$call}{$lexical} = $code;
        }
    }

    # Now we need to wrap our fatalised sub inside an itty bitty
    # closure, which can detect if we've leaked into another file.
    # Luckily, we only need to do this for lexical (autodie)
    # subs.  Fatal subs can leak all they want, it's considered
    # a "feature" (or at least backwards compatible).

    # TODO: Cache our leak guards!

    # TODO: This is pretty hairy code.  A lot more tests would
    # be really nice for this.

    my $installed_sub = $code;

    if ($lexical) {
        $installed_sub = $class->_make_leak_guard($filename, $code, $sref, $call,
                                                  $pkg, $proto);
    }

    $cache->{$cache_type} = $code;

    $install_subs->{$name} = $installed_sub;

    # Cache that we've now overridden this sub.  If we get called
    # again, we may need to find that find subroutine again (eg, for hints).

    $Is_fatalised_sub{$installed_sub} = $sref;

    return $sref;

}

# This subroutine exists primarily so that child classes can override
# it to point to their own exception class.  Doing this is significantly
# less complex than overriding throw()

sub exception_class { return "autodie::exception" };

{
    my %exception_class_for;
    my %class_loaded;

    sub throw {
        my ($class, @args) = @_;

        # Find our exception class if we need it.
        my $exception_class =
             $exception_class_for{$class} ||= $class->exception_class;

        if (not $class_loaded{$exception_class}) {
            if ($exception_class =~ /[^\w:']/) {
                confess "Bad exception class '$exception_class'.\nThe '$class->exception_class' method wants to use $exception_class\nfor exceptions, but it contains characters which are not word-characters or colons.";
            }

            # Alas, Perl does turn barewords into modules unless they're
            # actually barewords.  As such, we're left doing a string eval
            # to make sure we load our file correctly.

            my $E;

            {
                local $@;   # We can't clobber $@, it's wrong!
                my $pm_file = $exception_class . ".pm";
                $pm_file =~ s{ (?: :: | ' ) }{/}gx;
                eval { require $pm_file };
                $E = $@;    # Save $E despite ending our local.
            }

            # We need quotes around $@ to make sure it's stringified
            # while still in scope.  Without them, we run the risk of
            # $@ having been cleared by us exiting the local() block.

            confess "Failed to load '$exception_class'.\nThis may be a typo in the '$class->exception_class' method,\nor the '$exception_class' module may not exist.\n\n $E" if $E;

            $class_loaded{$exception_class}++;

        }

        return $exception_class->new(@args);
    }
}

# Creates and returns a leak guard (with prototype if needed).
sub _make_leak_guard {
    my ($class, $filename, $wrapped_sub, $orig_sub, $call, $pkg, $proto) = @_;

    # The leak guard is rather lengthly (in fact it makes up the most
    # of _make_leak_guard).  It is possible to split it into a large
    # "generic" part and a small wrapper with call-specific
    # information.  This was done in v2.19 and profiling suggested
    # that we ended up using a substantial amount of runtime in "goto"
    # between the leak guard(s) and the final sub.  Therefore, the two
    # parts were merged into one to reduce the runtime overhead.

    my $leak_guard = sub {
        my $caller_level = 0;
        my $caller;

        while ( ($caller = (caller $caller_level)[1]) =~ m{^\(eval \d+\)$} ) {

            # If our filename is actually an eval, and we
            # reach it, then go to our autodying code immediatately.

            last if ($caller eq $filename);
            $caller_level++;
        }

        # We're now out of the eval stack.

        if ($caller eq $filename) {
            # No leak, call the wrapper.  NB: In this case, it doesn't
            # matter if it is a CORE sub or not.
            if (!defined($wrapped_sub)) {
                # CORE sub that we were too lazy to compile when we
                # created this leak guard.
                die "$call is not CORE::<something>"
                    if substr($call, 0, 6) ne 'CORE::';

                my $name = substr($call, 6);
                my $sub = $name;
                my $lexical = 1;
                my $wrapper_pkg = $pkg;
                my $code;
                if (exists($reusable_builtins{$call})) {
                    $code = $reusable_builtins{$call}{$lexical};
                    $wrapper_pkg = undef;
                }
                if (!defined($code)) {
                    $code = $class->_compile_wrapper($wrapper_pkg,
                                                     1, # core
                                                     $call,
                                                     $name,
                                                     0, # void
                                                     $lexical,
                                                     $sub,
                                                     undef, # subref (not used for core)
                                                     undef, # hints (not used for core)
                                                     $proto);

                    if (!defined($wrapper_pkg)) {
                        # cache it so we don't recompile this part again
                        $reusable_builtins{$call}{$lexical} = $code;
                    }
                }
                # As $wrapped_sub is "closed over", updating its value will
                # be "remembered" for the next call.
                $wrapped_sub = $code;
            }
            goto $wrapped_sub;
        }

        # We leaked, time to call the original function.
        # - for non-core functions that will be $orig_sub
        # - for CORE functions, $orig_sub may be a trampoline
        goto $orig_sub if defined($orig_sub);

        # We are wrapping a CORE sub and we do not have a trampoline
        # yet.
        #
        # If we've cached a trampoline, then use it.  Usually only
        # resuable subs will have cache hits, but non-reusuably ones
        # can get it as well in (very) rare cases.  It is mostly in
        # cases where a package uses autodie multiple times and leaks
        # from multiple places.  Possibly something like:
        #
        #  package Pkg::With::LeakyCode;
        #  sub a {
        #      use autodie;
        #      code_that_leaks();
        #  }
        #
        #  sub b {
        #      use autodie;
        #      more_leaky_code();
        #  }
        #
        # Note that we use "Fatal" as package name for reusable subs
        # because A) that allows us to trivially re-use the
        # trampolines as well and B) because the reusable sub is
        # compiled into "package Fatal" as well.

        $pkg = 'Fatal' if exists $reusable_builtins{$call};
        $orig_sub = $Trampoline_cache{$pkg}{$call};

        if (not $orig_sub) {
            # If we don't have a trampoline, we need to build it.
            #
            # We only generate trampolines when we need them, and
            # we can cache them by subroutine + package.
            #
            # As $orig_sub is "closed over", updating its value will
            # be "remembered" for the next call.

            $orig_sub = make_core_trampoline($call, $pkg, $proto);

            # We still cache it despite remembering it in $orig_sub as
            # well.  In particularly, we rely on this to avoid
            # re-compiling the reusable trampolines.
            $Trampoline_cache{$pkg}{$call} = $orig_sub;
        }

        # Bounce to our trampoline, which takes us to our core sub.
        goto $orig_sub;
    };  # <-- end of leak guard

    # If there is a prototype on the original sub, copy it to the leak
    # guard.
    if (defined $proto) {
        # The "\&" may appear to be redundant but set_prototype
        # croaks when it is removed.
        set_prototype(\&$leak_guard, $proto);
    }

    return $leak_guard;
}

sub _compile_wrapper {
    my ($class, $wrapper_pkg, $core, $call, $name, $void, $lexical, $sub, $sref, $hints, $proto) = @_;
    my $real_proto = '';
    my @protos;
    my $code;
    if (defined $proto) {
        $real_proto = " ($proto)";
    } else {
        $proto = '@';
    }

    @protos = fill_protos($proto);
    $code = qq[
        sub$real_proto {
    ];

    if (!$lexical) {
        $code .= q[
           local($", $!) = (', ', 0);
        ];
    }

    # Don't have perl whine if exec fails, since we'll be handling
    # the exception now.
    $code .= "no warnings qw(exec);\n" if $call eq "CORE::exec";

    $code .= $class->_write_invocation($core, $call, $name, $void, $lexical,
                                       $sub, $sref, @protos);
    $code .= "}\n";
    warn $code if $Debug;

    # I thought that changing package was a monumental waste of
    # time for CORE subs, since they'll always be the same.  However
    # that's not the case, since they may refer to package-based
    # filehandles (eg, with open).
    #
    # The %reusable_builtins hash defines ones we can aggressively
    # cache as they never depend upon package-based symbols.

    my $E;

    {
        no strict 'refs'; ## no critic # to avoid: Can't use string (...) as a symbol ref ...
        local $@;
        if (defined($wrapper_pkg)) {
            $code = eval("package $wrapper_pkg; require Carp; $code");  ## no critic
        } else {
            $code = eval("require Carp; $code");  ## no critic

        }
        $E = $@;
    }

    if (not $code) {
        my $true_name = $core ? $call : $sub;
        croak("Internal error in autodie/Fatal processing $true_name: $E");
    }
    return $code;
}

# For some reason, dying while replacing our subs doesn't
# kill our calling program.  It simply stops the loading of
# autodie and keeps going with everything else.  The _autocroak
# sub allows us to die with a vengeance.  It should *only* ever be
# used for serious internal errors, since the results of it can't
# be captured.

sub _autocroak {
    warn Carp::longmess(@_);
    exit(255);  # Ugh!
}

1;

__END__

=head1 NAME

Fatal - Replace functions with equivalents which succeed or die

=head1 SYNOPSIS

    use Fatal qw(open close);

    open(my $fh, "<", $filename);  # No need to check errors!

    use File::Copy qw(move);
    use Fatal qw(move);

    move($file1, $file2); # No need to check errors!

    sub juggle { . . . }
    Fatal->import('juggle');

=head1 BEST PRACTICE

B<Fatal has been obsoleted by the new L<autodie> pragma.> Please use
L<autodie> in preference to C<Fatal>.  L<autodie> supports lexical scoping,
throws real exception objects, and provides much nicer error messages.

The use of C<:void> with Fatal is discouraged.

=head1 DESCRIPTION

C<Fatal> provides a way to conveniently replace
functions which normally return a false value when they fail with
equivalents which raise exceptions if they are not successful.  This
lets you use these functions without having to test their return
values explicitly on each call.  Exceptions can be caught using
C<eval{}>.  See L<perlfunc> and L<perlvar> for details.

The do-or-die equivalents are set up simply by calling Fatal's
C<import> routine, passing it the names of the functions to be
replaced.  You may wrap both user-defined functions and overridable
CORE operators (except C<exec>, C<system>, C<print>, or any other
built-in that cannot be expressed via prototypes) in this way.

If the symbol C<:void> appears in the import list, then functions
named later in that import list raise an exception only when
these are called in void context--that is, when their return
values are ignored.  For example

    use Fatal qw/:void open close/;

    # properly checked, so no exception raised on error
    if (not open(my $fh, '<', '/bogotic') {
        warn "Can't open /bogotic: $!";
    }

    # not checked, so error raises an exception
    close FH;

The use of C<:void> is discouraged, as it can result in exceptions
not being thrown if you I<accidentally> call a method without
void context.  Use L<autodie> instead if you need to be able to
disable autodying/Fatal behaviour for a small block of code.

=head1 DIAGNOSTICS

=over 4

=item Bad subroutine name for Fatal: %s

You've called C<Fatal> with an argument that doesn't look like
a subroutine name, nor a switch that this version of Fatal
understands.

=item %s is not a Perl subroutine

You've asked C<Fatal> to try and replace a subroutine which does not
exist, or has not yet been defined.

=item %s is neither a builtin, nor a Perl subroutine

You've asked C<Fatal> to replace a subroutine, but it's not a Perl
built-in, and C<Fatal> couldn't find it as a regular subroutine.
It either doesn't exist or has not yet been defined.

=item Cannot make the non-overridable %s fatal

You've tried to use C<Fatal> on a Perl built-in that can't be
overridden, such as C<print> or C<system>, which means that
C<Fatal> can't help you, although some other modules might.
See the L</"SEE ALSO"> section of this documentation.

=item Internal error: %s

You've found a bug in C<Fatal>.  Please report it using
the C<perlbug> command.

=back

=head1 BUGS

C<Fatal> clobbers the context in which a function is called and always
makes it a scalar context, except when the C<:void> tag is used.
This problem does not exist in L<autodie>.

"Used only once" warnings can be generated when C<autodie> or C<Fatal>
is used with package filehandles (eg, C<FILE>).  It's strongly recommended
you use scalar filehandles instead.

=head1 AUTHOR

Original module by Lionel Cons (CERN).

Prototype updates by Ilya Zakharevich <ilya@math.ohio-state.edu>.

L<autodie> support, bugfixes, extended diagnostics, C<system>
support, and major overhauling by Paul Fenwick <pjf@perltraining.com.au>

=head1 LICENSE

This module is free software, you may distribute it under the
same terms as Perl itself.

=head1 SEE ALSO

L<autodie> for a nicer way to use lexical Fatal.

L<IPC::System::Simple> for a similar idea for calls to C<system()>
and backticks.

=for Pod::Coverage exception_class fill_protos one_invocation throw write_invocation ERROR_NO_IPC_SYS_SIMPLE LEXICAL_TAG

=cut